Friday, November 9, 2007

[oopic] Re: OOPIC and CMUCAM

--- In oopic@yahoogroups.com, "rtstofer" <rstofer@...> wrote:
>
> --- In oopic@yahoogroups.com, "teh_gamr" <ashraf.hammoud@> wrote:
> >
> > Hello all,
> >
> > I'm intending to build some kind of object following robot, perhaps a
> > colorful ball. Tracking with the cmucam is a piece of cake, as long as
> > the lighting is right. The camera automatically rotates the servo.
> >
> > However, I need some way for the oopic to know where the camera is
> > pointing and move the base station accordingly.
> >
> > I can think of 2 ways:
> >
> > 1) Have the camera talk directly to the oopic. From searching online,
> > I couldn't find much to help me.
> >
> > 2) Have the oopic read the position of the servo that the camera is
> > mounted on.
> >
> > Does anyone have an idea how to have the oopic talk to a cmucam? I
> > know it's possible, I have the final report for a project that used
> > an oopic with a cmucam connected serially, but there aren't any
> > connection details.
> > On the other hand, is there any way that I can tap into the control
> > line of the servo to know where it is pointing or what angle it's been
> > given?
> >
>
>
> I have heard rumors that it might be possible to keep up with an
> abbreviated Track command but the OOPic is so slow at executing code
> that I think it wouldn't leave much time for anything else
>
> I would try to read the servo pulse width with a PAK-VII chip:
> http://www.awce.com/pak7.htm
>
> Sample code here:
> http://www.awce.com/ooppic7.htm
>
> Or, you could do something with optical encoding like a wheel with
> stripes in some kind of Grey code. Mechanically, it might be
> difficult but you could also try a rotary encoder (nothing but a fancy
> potentiometer if you use the analog type).
>
> I think I like the PAK-VII approach...
>
> Richard
>

I'm doing this as a project for a university course. If it makes any
difference, they've got a lot of equipment lying around. I can have as
many oopics as I need. They've also got cmucam2's.

Would it help if I had the processing power of more than one oopic?

Also, this is from the cmucam2's manual:

"For even slower processors, the camera can operate in "poll mode". In
this mode, the host processor can ask the CMUCAM2 for just a single
packet of data. This gives slower processors the ability to more
easily stay synchronized with the data."

I'm thinking... I only need the X position to move the base of my
robot. One sample a second is plenty fine. Can't the oopic do even that?

Failing that idea, the PAK-VII seems a great idea. Problem is, I'm in
the middle east and things take time to get shipped. I'll talk to my
instructor tomorrow.

Thanks for your help


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